Although an affinity between persons are caused by empathy of having the same emotion with respect to the same target, senses of values, characters, and the like, it takes a long time to know whether or not a mutual affinity is good, and it is not possible to precisely know it merely from a several-hour interaction, for example.
In relation to technologies of extracting and visualizing relations between humans, Patent Literature 1 below, for example, describes a relation diagram that represents mutual intimacies, which have been calculated on the basis of smiling levels of respective persons who appear in an image together by processing image data, by distances and also describes a time-series change diagram of the relation diagram.